A case of trisomy for the proximal portion of the long arm of chromosome 13 is described in a child who has a few congenital defects. This anomaly has been traced to a balanced 6/13 chromosomal translocation in the mother. A review of six cases, also trisomic for the proximal portion of the long arm, makes it possible to delineate a new clinical entity in which a small number of the clinical findings, commonly observed in the full trisomy 13, are present.